Not Applicable.
Not Applicable.
1. Field of the Invention
This invention relates to an optical system and associated mechanics for a flashlight providing a heretofore-unachievable level of performance.
2. Description of the Related Art
The flashlight was invented in 1898 by Conrad Hubert who turned a metal tube, a light bulb and a battery into the world""s first flashlight. Little has changed in flashlight technology until now with this invention.
Today""s flashlight technology is based on locating a tungsten lamp or bulb at the focus of a parabolic reflector and simply imaging the filament out into object space. The reflector may be of other shapes and may be faceted or otherwise modified. At a somewhat distant wall (such as at a distance of 3-6 feet for example) a crude image of the filament will be formed.
A significant problem with the current technology is that the image of the filament is generally a crude image or spot which varies significantly in its intensity. While some flashlights permit the user to vary or adjust the size of the pattern, it is generally highly non-uniform in intensity. Another problem is that the light spills out to a wide area outside of the intended spot area.
Another problem is that with the inherent non-uniformity of the spot as discussed above, it makes it difficult in many circumstances to see clearly the object of interest. This is because the variation in intensity can often mask or hide the features of the object of interest.
Another problem is that the illuminated area with prior art flashlights is unattractive. Most illumination in homes and offices for example provide reasonably uniform brightness and we are generally use to such uniformity in brightness.
One or more of the problems outlined above may be addressed by the various embodiments of the invention. Broadly speaking, techniques according to the invention use a light homogenization method to provide a uniform pattern of light on an object. The pattern of light appears uniform in brightness to the eye, and, particularly with those embodiments using a light pipe, the pattern of light has a very sharp edge defining its shape, much like a theater spotlight. Certain embodiments of the invention provide a higher level of light or photon efficiency than prior art technology flashlights in addition to providing the bright uniform pattern of light. In addition, a light modifying component can be used to manipulate the pattern of light into particular shapes and images.
In one embodiment, a light source according to an embodiment of the invention projects light into an input face of a light pipe. The light travels along the light pipe reflecting off its walls such that the light exiting the output face of the light pipe is homogenized, and of a more uniform intensity that the light which entered at the input face. A lens is used to reimage the uniform light exiting the output face onto the object or area of interest. The light sources which may be used include: common flashlight bulbs, light emitting diodes, arc lamps and the like. Light directing devices such as elliptical reflectors, diffusers and the like, may be used to channel light from the light source into the light pipe. Light pipes can be solid or hollow, can be tapered or uniform, or can be a compound parabolic concentrator, or the like. Light modifying components can be used in the system to create patterns and display images and include masks, films, transparencies and the like.
Other embodiments accomplish light homogenization using lens arrays to achieve a uniform pattern of light. Such lens arrays can be used alone or in a series to diffuse an original uneven light projection into a resulting more uniform pattern of light. As the number of lens arrays used, and/or the number lenslets used in such lens arrays are increased, the greater the amount of resulting homogenization is generally achieved.